The government says it has closed the Mountain Road due to pressures on emergency services.
A DoI post said: “Due to current significant pressures on emergency services, the A18 Mountain Road (Ramsey to Creg Ny Baa) will be closed with immediate effect.
“This decision has been taken in the interests of public safety, ensuring emergency crews can respond effectively and without delay across the network.
“All road users are reminded to ride and drive to the prevailing conditions and to do so responsibly at all times. The situation will be kept under review and the road will reopen as soon as it is safe and appropriate to do so.”